The present invention relates to mixing solid pieces with a liquid, and more particularly, but not exclusively, relates to coating and coloration of landscaping materials.
The problem of landfill crowding has grown steadily. One way to reduce this crowding is to recycle as many materials as possible. One type of material suitable for recycling is wood. Wood may arrive at the landfill from a natural source, such as discarded tree branches, or it may be derived from various discarded products, such as shipping crates and furniture.
One way to recycle wood is to reduce the wood to a number of pieces of generally uniform size with a shredder, chipper, or grinder. Such comminuted wood is often suitable for use as a landscaping mulch. However, the varied types of wood typically obtained from a landfill often result in a non-uniform coloration that significantly changes with age and exposure to the elements. To alleviate this problem, recycled wood pieces are sometimes treated with a colorant to provided a more pleasing appearance. U.S. Pat. No. 5,308,653 to Rondy describes one coloring process.
One problem often encountered with coloring processes is excessive run-off of liquid colorants used to impart a uniform appearance to the wood pieces. This run-off adversely impacts cost effectiveness. To address this problem, there is a need to optimize the coloration process by determining the minimum amount of liquid colorant needed for a given amount of wood. There also remains a need to provide a more cost effective way to uniformly color landscaping material.
Another problem with the coloration process is that mixers used to blend liquid colorant and wood pieces are subject to frequent jamming. Typically, the mixer becomes packed with a mass of wood chips that are stuck together. This mass of chips often prevents discharge of the treated product from the mixer. Equipment down time to unclog the mixer generally increases processing costs and may result in excessive colorant run-off. Thus, there is also a need for a mixing system which resists packing and still economically imparts a uniform color to landscaping materials.
One form of the present invention is a system with a mixer defining a chamber that has an opening for inserting solid pieces therein. The chamber is in fluid communication with a conduit. Furthermore, the system has a source of a liquid agent and a metering device to selectively provide the agent from the source to the conduit. A water supply is coupled to the conduit to dilute the agent prior to reaching the pieces in the chamber. A controller is operatively coupled to the metering device to provide a delivery signal. The metering device responds to the delivery signal to adjust delivery of the agent to the conduit from a first non-zero rate to a second non-zero rate.
In an alternative form of the present invention, water and a colorant are mixed to produce a colorant liquid mixture during the movement of wood chips within a mixing chamber. Colorant supply to the liquid mixture is metered to control colorant amount or concentration in the mixture. The liquid mixture is put into the chamber to color at least a portion of the chips. The chips are discharged from the chamber. In one variation of this feature, landscaping gravel or rocks may be colored with the mixing process. In another variation, the mixture imparts a clear coating to rocks or another landscaping material to provide a high gloss appearance.
Among other alternative forms of the present invention are a mixing system with a vessel for supplying a liquid and a device for supplying solid pieces to mix with the liquid. The system has an elongated enclosure with a first end opposing a second end. The enclosure defines a chamber in fluid communication with the vessel to receive the liquid. The chamber also has an inlet and an outlet with the inlet being closer to the first end than the outlet. The chamber receives the pieces from the device through the inlet and discharges the pieces through the outlet. A motor driven mixing auger positioned in the chamber between the first and second ends rotates about a rotational axis to intermix the liquid and pieces. The auger includes a first helical flight between the inlet and the outlet to convey the pieces from the inlet to the outlet when the auger is rotated. The auger also includes a second helical flight between the first flight and the second end. The second flight has a length along the rotational axis shorter than the first flight. The second flight may have a rotational direction opposite the first flight and be positioned at least partially over the outlet to reduce clogging. In one variation of this system, the liquid may be a colorant and the solid pieces may include wood chips to be intermixed with the liquid to attain a generally uniform color.
In yet another alternative form, the first and second flights are mounted about an elongated shaft configured to rotate about the rotational axis and a portion of the first flight does not contact the shaft while turning about the rotational axis for at least three revolutions, defining a space therebetween. This structure enhances intermixing of the wood pieces with the liquid.
In still another alternative form, a mixing technique includes moving a number of wood chips through a generally horizontal, elongated passage of a mixer from a top inlet adjacent a first end of the mixer to a bottom outlet adjacent a second end of the mixer. This movement is performed by turning a pair of augers disposed within the passage. The inlet and outlet are spaced apart from one another along a longitudinal axis of the mixer. A liquid colorant and water are mixed to provide a liquid coloring mixture during movement of the wood chips. This mixing is regulated with a controller. The mixture is provided to a spray hood to impart color to the wood chips while moving. The spray hood defines a chamber projecting above the passage and having a plurality of nozzles that deliver the mixture to the chamber under pressure. The chamber intersects the passage to define an area for contacting the wood chips with the mixture. This area is positioned generally opposite the nozzles to extend along the longitudinal axis of the mixture at least about two-thirds of a distance between the inlet and the outlet. Further, this area transversely spans across at least about three-fourths of a top width of the passage occupiable by the wood chips. The wood chips are discharged through the outlet. It has been found that this arrangement facilitates reduction of the amount of water needed to adequately color the wood chips.
In a further alternative form, a mixing technique includes moving a number of wood chips within a mixing chamber and blending water and a colorant in a static mixer while the wood chips are moving to produce a generally homogenous liquid colorant mixture for supply to the chamber. The mixer includes a cavity containing one or more internal baffles oriented to mix the water and colorant. The colorant is metered to the mixture with a variable rate pump responsive to a controller while maintaining a generally constant flow rate of the water to the mixture with a flow rate regulator. A coloring property of the wood chips is determined and concentration of the colorant in the mixture is adjusted from a first non-zero amount to a second non-zero amount in accordance with the coloring property. This adjustment includes changing delivery rate of the colorant to the mixture with the controller. At least a portion of the wood chips are colored in the chamber with the mixture. The wood chips are then discharged from the chamber.
Accordingly, it is one object of the present invention to provide a system that dispenses a liquid to a mixer for blending with solid pieces therein.
It is another object of the present invention to optimize the mixing of a concentrated liquid agent with water to create a liquid mixture for supply to the chamber of a mixer for blending with solid pieces. The agent may include a colorant or clear coat material and the solid pieces may comprise landscaping material such as wood chips or rocks.
It is still another object to color wood chips to provide a mulch. Preferably, the coloration technique reduces the amount of water needed to apply a water-based colorant mixture to the chips and the amount of colorant mixture run-off.
An additional object of the present invention is to provide a mixer which resists packing of solid pieces being blended with a liquid therein.
Further objects, features, aspects, benefits, and advantages of the present invention shall be apparent from the detailed drawings and descriptions provided herein.